@incollection{GreenhalghBenfordDrozdetal., author = {Greenhalgh, Chris and Benford, Steve and Drozd, Adam and Flintham, Martin and Hampshire, Alastair and Oppermann, Leif and Smith, Keir and Tycowicz, Christoph von}, title = {EQUIP2: A Platform for Mobile Phone-based Game Development}, series = {Concepts and Technologies for Pervasive Games - A Reader for Pervasive Gaming Research}, volume = {1}, booktitle = {Concepts and Technologies for Pervasive Games - A Reader for Pervasive Gaming Research}, publisher = {Shaker Verlag}, isbn = {978-3-8322-6223-5}, pages = {153 -- 178}, language = {en} } @article{HildebrandtSchulzTycowiczetal., author = {Hildebrandt, Klaus and Schulz, Christian and Tycowicz, Christoph von and Polthier, Konrad}, title = {Interactive spacetime control of deformable objects}, series = {ACM Transactions on Graphics}, volume = {31}, journal = {ACM Transactions on Graphics}, number = {4}, publisher = {ACM}, doi = {10.1145/2185520.2185567}, pages = {71:1 -- 71:8}, abstract = {Creating motions of objects or characters that are physically plausible and follow an animator's intent is a key task in computer animation. The spacetime constraints paradigm is a valuable approach to this problem, but it suffers from high computational costs. Based on spacetime constraints, we propose a technique that controls the motion of deformable objects and offers an interactive response. This is achieved by a model reduction of the underlying variational problem, which combines dimension reduction, multipoint linearization, and decoupling of ODEs. After a preprocess, the cost for creating or editing a motion is reduced to solving a number of one-dimensional spacetime problems, whose solutions are the wiggly splines introduced by Kass and Anderson [2008]. We achieve interactive response using a new fast and robust numerical scheme for solving a set of one-dimensional problems based on an explicit representation of the wiggly splines.}, language = {en} } @misc{NavaYazdaniHegevonTycowiczetal., author = {Nava-Yazdani, Esfandiar and Hege, Hans-Christian and von Tycowicz, Christoph and Sullivan, T. J.}, title = {A Shape Trajectories Approach to Longitudinal Statistical Analysis}, issn = {1438-0064}, url = {http://nbn-resolving.de/urn:nbn:de:0297-zib-69759}, abstract = {For Kendall's shape space we determine analytically Jacobi fields and parallel transport, and compute geodesic regression. Using the derived expressions, we can fully leverage the geometry via Riemannian optimization and reduce the computational expense by several orders of magnitude. The methodology is demonstrated by performing a longitudinal statistical analysis of epidemiological shape data. As application example we have chosen 3D shapes of knee bones, reconstructed from image data of the Osteoarthritis Initiative. Comparing subject groups with incident and developing osteoarthritis versus normal controls, we find clear differences in the temporal development of femur shapes. This paves the way for early prediction of incident knee osteoarthritis, using geometry data only.}, language = {en} }